Recently, along with the wider spread of a mobile terminal on which there is mounted an image pickup device using a solid-state image sensor such as a CCD-type image sensor and a CMOS-type image sensor, a mobile terminal on which there is mounted an image pickup device using an image sensor having a larger number of pixels so as to obtain a higher quality image has become available on the market. So far, the image sensor having a larger number of pixels was accompanied by a larger size, but recently, higher resolution of the pixel has advanced and the size of the image sensor has become smaller. While a high resolution is required for an image pickup lens used with the image sensor having such a higher-resolution pixel, since resolution is restricted by an F-number and a higher resolution can be obtained by a faster or brighter lens having a smaller F-number, a sufficiently high performance has not been realized by a conventionally used F-number of approximately F/2.8. Accordingly, there has been required a faster image pickup lens having an F-number of 2 or less, which is suitable for an image sensor having a larger number of pixels, a higher-resolution pixel, and a smaller size. As an image pickup lens for such an application, a five-element structure image pickup lens, which allows a higher aperture ratio and a higher performance than a three-element or four-element structure lens, is disclosed in a patent publication.
For the five-element structure image pickup lens, there is disclosed an image pickup lens configured with a front group which includes, in order from the object side, a first lens having a positive or negative refractive power, a second lens having a positive refractive power, an aperture stop, and a rear group which includes a third lens having a negative refractive power, a fourth lens having a positive refractive power, and a fifth lens having a negative or positive refractive power (refer to patent literatures 1 and 2, for example).